Opinions of my door skin patch

[Sparky]

I’m looking to get better at oxy/Ace fusion welding in sheet metal, and have a door with a skin that has multiple damage in many areas, but I will focus on one area for now. It has rust holes on the bottom corners, and old repair in the middle I found under the filler, and this leading edge damage. I believe a complete new door skin would be the proper repair, but I want to use this to learn some lessons.
This damage is full of thick weld on top of weld, and has limited access to the back side for a dolly.

A thin pancake dolly can just barely fit in behind the area due to the inner structure.

I made up a template, cut out a repair patch of the same thickness sheet metal which was approximately .036” 20 ga. Bent the ridge, and used a series of light hammer blows to put a slight crown it it to match the door. I’m following the techniques in David Gardiners DVD.

I followed Roberts suggestion I saw somewhere on making sure not to have 90 degree turns to prevent concentrated hot spots. I scribed the outline of the patch, and cut out the damage with a thin cutoff wheel, then used a dremel to sneak up to the scribe line.

Using magnets to hold it I began to tack it in with the torch after I practiced on some same gauge metal, using a small smith torch I picked up on eBay. I only had a large body torch, this one is half the size and a lot lighter. Of course the first tack I blew through the thin metal.

I hammer/dolly each tack as this thin metal was distorting very easy and quickly. I made it all around following this sequence with a few blow outs.

after I had the metal relatively straight, I proceeded to fusion weld from right to left, in one pass as the DVD shows. the black areas are where I needed to add filler rod.

This really distorted the metal and took about 2-3 hours of hammer/dolly and then slapper or Flipper as David calls it on the dolly. It left me with two high spots I need to shrink, one on the top half above the welded area (1 o’clock), and one on the lower half below the welded area (4 o’clock).

I kept filing the welded as I worked the metal to see the highs and lows. Here is where I’m at. Today ( right now) I’m going to shrink the two high spots with the torch, dolly, and hammer.

This is for a 68 Firebird, and obviously there are door skins available, but if this was for a more obscure car, with no aftermarket metal available would you have done this differently? I don’t think I can really metal finish it completely due to the limited access to the back side. I would really need to cut out part of the inner structure to get at all of the repair near the edges. After I get the high spots down, I should be under an 1/8” of filler to cover it. I appreciate any views on what I did, or should have done, it’s how I learn.

thanks
Chris

 

[Chris_Hamilton]

I think you are doing a pretty good job. Kudos for gas welding it. You are definitely getting the hang of welding with the torch.

Smallish patch like that welded with gas is going to distort but that was in an odd place so you really had no choice. Only glaring thing to me is that you should have left enough material so you could fold it over the flange like the rest of the skin. But you can make a piece and weld it in. For that I would MIG it (if you have one). And your fit was pretty good judging from the pic but you could have made it slightly tighter and most likely you would not have had to use rod.
And if you shrink with heat you don't need to back it up with the dolly, just use the same tip that you did welding, heat the area up to a dull red (and dull red isn't absolutely neccesary you can still shrink at lesser temps) and tap the high (volcano) with your hammer. Even as it is cooling you can still shrink so keep tapping. Light, light blows. Let it cool and check your progress.
Also If you can get your flipper (slapper) between the door brace and skin you can use it as a dolly to stretch the edge.

But all in all very nicely done.

 

[shine]

gas welding will always create less distortion than other welds and will finish better . tig welding comes close .

 

[John Long]

Unless you are very, very skilled, I would not do the final weld with one pass. David Gardner may be able to do a great job of that but it is not something even most skilled metal workers would try. By completing your patch with small tacks and planishing the panel, as you go, you can keep it straight and not let it get away from you.

John

 

[John Long]

gas welding will always create less distortion than other welds .

I never used anything but a O/A torch for years. and at one time considered myself to be pretty good. It is, however, a method requiring a very high level of skill and will not be mastered without much practice. As the years have gone by, I have more and more gone to the mig rather than spend the time and effort required to make a large patch with gas.

I personally can mig a patch in wih less distortion than a gas weld by turning the mig up hot and using very, very short duration zaps. The problem is the mig weld will be much harder to planish back to it's original shape than the gas weld, which will remain more malleable.

When you reach the point where you have mastered the torch, you indeed have reason to be proud. The secret is never let the distortion to get away from you. Planish as you go focusing on the area of the weld, inside the HAZ. (Heat affected zone.)

John

This is a door skin I wheeled.



Mig welded.



2 Coats of SPI epoxy..... no filler. Though, it did need and receive some before paint.

 

[chevman]

John, have you tried tig welding? I have a small smith gas torch and low pressure regulators, and I know gas is preferred, but I prefer the tig by far. The metal seems to work just as good, and it makes less distortion. I can keep welding quite a ways before stopping, and if the seam is tight, then I can turn the heat up and fusion weld fast enough to have very little distortion.

 

[John Long]

I own a TIG. I bought it about 6 years ago but have not used it enough to brag on my ability. I also have a new Henrob torch and likewise have not used it enough to know whether I would like it or not. (it was given to me by my nephew who did not like it.)

When Barb's health began to fail, my attention shifted to getting the Bel Air back together, and I have spent way less time experimenting or educating myself. I used to delight in trying new methods or practicing a technique that maybe I saw someone do on one of the metal shaping sites. Time is so scarce and precious at this point, I am pretty much just trying to get it done.

John

 

[John Long]

Sparky. I hope you don't feel like we hijacked your thread. I know we all admire what you are doing and how you are doing it. We all are just offering our own experiences and reasons for why we do things as we do.

Keep up the good work and post more pictures as you make progress. Metal working is addictive, for sure.

John

 

['68 Coronet R/T]

Sparky,
I am no expert by any means. You are off to a great start and I am sure will refine your technique. Small patches can heat up very quickly thus causing distortion. I find that spacing the spot welds farther apart helps to reduce this. The first few spots are strategically placed just to hold the patch in place. The next round will be spaced evenly between the spots and so on until I have to begin extending the spot welds until they form a nice seam.

 

[MP&C]

Chris, Kudos for having the stones to try out the torch, most won't give that a go on something like a door skin.. Looks like you did a nice job, I'll add some suggestions that may help if someone else wants to try this as well...

If I were doing a lower door skin, one side to the other, I would start the tacking on one end and work toward the other. Given your patch is only the center portion of one end, I would start the tack at the middle, where the high part of the crease is located, simply to lock that in place. Starting at one end, given the shrinking that goes with welding, may cause the crease to pull toward the side that was started first, so it may help to keep it aligned by tacking it first, then work your way around. Keep an eye on crease alignment as you go, change sides if it needs to pull the other way...

Next, based on the instructional video that Peter Tommasini put out on gas welding, he says that once you make your first tack, the next tack is placed where the outer band of the HAZ of the first tack crosses the seam in the metal. It's hard to see where yours are placed, but I think some may be a bit too far apart. I only say that as the HAZ along the finished tacks move in and out a bit. I've noticed in following Peter's suggestion for placement of subsequent tacks that the HAZ is a little more consistent in width. Which is a major key in welding as starts and stops result in the worst distortion, the more continuous or consistent we can be in our efforts, the easier it will be to keep things distortion free. Here is a 1/4 scale racing tractor fender that was in the shop a couple weeks ago, notice the HAZ shows a little better consistency in width by following Peter's instruction on locating any subsequent tacks. Even around the curve of the fender, after tacking you could hardly feel any distortion, which should make any planishing efforts easier and more consistent in methods as well.

 

[MP&C]

Unless you are very, very skilled, I would not do the final weld with one pass. David Gardner may be able to do a great job of that but it is not something even most skilled metal workers would try. By completing your patch with small tacks and planishing the panel, as you go, you can keep it straight and not let it get away from you.

John

John, if you're ever out this way, please stop by for a day or so. I have the same feeling for the Henrob as your nephew, but really love the Meco torch for gas welding. I find it quicker to remove heat and thus blowouts than the TIG, or perhaps it seems as the "pressure" is less than that of the shielding gas of the TIG. When the above tractor fender was welded (after tacks completed), it was done in one pass. There were a couple spots that wanted to blow, and this was easily averted by lifting the heat, then back in again with another dab of filler.. I am far from the expertise of David or Peter, but find the Meco makes gas welding enjoyable, and think I'd change your mind on continuous pass gas welding in about an hour or so...

 

[Sparky]

Thanks for sharing your knowledge guys, I really appreciate it. Chris I didn’t fold a seam over because the old was welded so much in that area, I left it, and figured I would just weld the leading edge with the mig as you suggested. The fit was perfect but as Robert pointed out, I should have started at the middle body line. (That thought crossed my mind) As predicted that caused it to pull a slight gap which caused the burn throughs. Good point on getting the slapper in there as a dolly.
John thanks for your thoughtful input here, and I don’t think anyone hi jacked anything. These posts just flow, and I go with it. I have a mig and tig, but am just enamored by the torch, and want to give it an honest try. David and Peter make it look so easy, but like you said that comes with experience.
Robert, very good points, you hit on things that crossed my mind while I was planning my approach, but with my lack of experience I made key mistakes, or as I like to call them learning experiences. On the placement of the tacks, I was confused to which part of the HAZ peter is taking about (his YouTube vid), the outermost color zone, or the next gray zone (which would be closer together). I chose the outermost zone which was probably too far. You brought up a good point on lifting the heat when a blowout is ready to happen. That is something I need to pay more attention too.

This door skin is much thinner than the 18ga test coupons I’ve been practicing on. Much more challenging. Being able to place the welded test coupons pieces on a dolly and hammer all the distortion out, made me feel like Superman, but the door skin put me back in my place, Lol.

I’m putting the doors and fenders on before I go any further, to see where my lines and contours are. I’ll keep my progress posted. Thanks to all of you.

 

[MP&C]

The location Peter was talking about is where discoloration meets the unaffected color.

I agree with Chris, a flange should have been folded (missed that). Welding the flange on is recipe for distortion, and then you’re back where you started.

 

[Chris_Hamilton]

I have found also that gas welding new steel to old steel it sometimes welds very differently than when welding 2 pieces of new steel together like with your coupon. Why that is I don't know but I have also heard Kent White mention it in one of his videos.
One other thing that you might find helpful, when you need rod instead of using the standard 1/16 tig rod, you can also try annealed mechanics wire, or when you want/need something smaller than the 1/16 tig rod, straightened .035 MIG wire works well. Lot of times that's just enough wire to do patches like yours and keep from blowing through without adding too much to the weld puddle.
Oh and Peter recommends using rod when making your tacks. Also you should let each tack cool before doing the next one. Don't hammer on a hot tack or you will shrink it. So doing a steel patch with gas takes some time.
Just my opinion but with smaller areas and hard to planish areas you are better off with the MIG and spotting it (connect the dots) as you will get a lot less distortion. (but any you do get is a lot harder to planish out) Gas welding works best in situations like Robert showed above, or with a door skin forming and replacing a complete section preferably just below a body line or curve in the panel like Robert referred to in the above post. At a curve or line the panel is stronger there and more resistant to distortion. Also try to plan your sections so that you can access them to planish the distortion out. Lots of times this means removing a lot more than just the local damage.
Keep it up you are doing great.

 

[Chris_Hamilton]

If you haven't discovered Peter Tommasini's videos yet you need to get the set. Trust me, they are excellent. In #'s 7, 8, and 9 he shows from start to finish how to make a 1/4 panel for a 1960's Monaro (Aussie Chevelle) with nothing more than a English wheel, big sandbag and handtools. Plus he is excellent at explaining what he is doing, why he is doing it and what happens if you do it wrong. Excellent and well worth the money.

http://www.handbuilt.net.au/dvds.html

10 DVD Set is $400 Australian which as of today is roughly $270 USD. Well worth it.

 

[Sparky]

The location Peter was talking about is where discoloration meets the unaffected color.

I agree with Chris, a flange should have been folded (missed that). Welding the flange on is recipe for distortion, and then you’re back where you started.

Perhaps my initial tacks took too long to make( had the heat on the panel too long) and consequently caused larger HAZ zone, which then spaced my tacks too far apart. I see how your HAZ is more even on that fender. I’m gonna look up Peters DVD set. I’ve watched him online and he got my attention real quick.
Yeah that flange, or lack of was a rookie mistake.
I’m installing new body bushings on the sub frame, so I can hang the doors and fenders to see where the gaps and crown alignments are before I go any further.

 

[Sparky]

If you haven't discovered Peter Tommasini's videos yet you need to get the set. Trust me, they are excellent. In #'s 7, 8, and 9 he shows from start to finish how to make a 1/4 panel for a 1960's Monaro (Aussie Chevelle) with nothing more than a English wheel, big sandbag and handtools. Plus he is excellent at explaining what he is doing, why he is doing it and what happens if you do it wrong. Excellent and well worth the money.

http://www.handbuilt.net.au/dvds.html

10 DVD Set is $400 Australian which as of today is roughly $270 USD. Well worth it.

Thanks Chris! Perfect timing, I’m ordering his DVD’s now. It will be interesting comparing David’s and Peter’s approach.

 

[Bentrustynail]

Robert, I have two meco midgets and hate them both. Peter agrees with that - the flame is harsh. Kent White even sent me some experimental tips since he also acknowledges the harsh flame, they were a bit better but still not great. The Meco Aviator Jet on the other hand is the best thing since sliced bread. Beautiful quiet smooth flame, feels great in the hand. I need to sell my Midgets.

Oh, and Sparky, I notice many people start their tacks exactly on the cut line, that is a recipe for a blown hole, start your flame slightly off to one side - on one of the pieces then wash the flame over to the other side and back again, the tack will form where you want it with no blow hole. This takes only a second, if there's a slight gap (which is a blown hole waiting to happen) heating one side will expand the steel and fill the gap before you wash the flame over to the second piece and the joint line. Try it.

 

[John Long]

I hesitated to mention this as I thought you guys would think I'm nuts but.........I use a number two tip for body panels. A #00 that a lot of guys use puts out enough velocity that it would pop or blow out due to how far you have to turn it up. The #2 allows me to turn the torch down for a soft flame with enough heat for a quick weld. Also, I like 3/32 CC rods that I can brush the flame up on as well as absorbing some heat when needed thus allowing me to take the heat away from the panel as needed. Doing the "dance" between rod and panel and air is what makes for a good penetrating weld without a tremendous amount of weld needing ground.

No way do I claim my method is best. It is what I came up with in about 1980 when I became interested in metal forming and what I became comfortable with.

Here is a section of my floorboard I tipped the edge with gas and gas welded on the '53. It allowed me to make this panel in one piece and move the weld away from the bend.

Bare in mind, this was a floorboard for what will be a nice driver. My goal was not to make a fusion weld that could be metal finished.

John

 

[John Long]

John, if you're ever out this way, please stop by for a day or so. I have the same feeling for the Henrob as your nephew, but really love the Meco torch for gas welding. I find it quicker to remove heat and thus blowouts than the TIG, or perhaps it seems as the "pressure" is less than that of the shielding gas of the TIG. When the above tractor fender was welded (after tacks completed), it was done in one pass. There were a couple spots that wanted to blow, and this was easily averted by lifting the heat, then back in again with another dab of filler.. I am far from the expertise of David or Peter, but find the Meco makes gas welding enjoyable, and think I'd change your mind on continuous pass gas welding in about an hour or so...


View attachment 9971

Be careful what you offer Robert. Southern Maryland is not that far away.......

It would be my honor to spend a little time at your shop. Who knows. Maybe someday. .....

John